/*
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE
 * file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file
 * to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the
 * License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 */
package com.blade.web.multipart;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * Utility class for working with streams.
 */
public final class Streams {

	/**
	 * Private constructor, to prevent instantiation. This class has only static methods.
	 */
	private Streams() {
		// does nothing
	}

	/**
	 * Default buffer size for use in {@link #copy(InputStream, OutputStream, boolean)}.
	 */
	private static final int DEFAULT_BUFFER_SIZE = 8192;

	/**
	 * Copies the contents of the given {@link InputStream} to the given {@link OutputStream}. Shortcut for
	 *
	 * <pre>copy(pInputStream, pOutputStream, new byte[8192]);</pre>
	 *
	 * @param pInputStream The input stream, which is being read. It is guaranteed, that {@link InputStream#close()} is
	 *            called on the stream.
	 * @param pOutputStream The output stream, to which data should be written. May be null, in which case the input
	 *            streams contents are simply discarded.
	 * @param pClose True guarantees, that {@link OutputStream#close()} is called on the stream. False indicates, that
	 *            only {@link OutputStream#flush()} should be called finally.
	 *
	 * @return Number of bytes, which have been copied.
	 * @throws IOException An I/O error occurred.
	 */
	public static long copy(InputStream pInputStream, OutputStream pOutputStream, boolean pClose) throws IOException {
		return copy(pInputStream, pOutputStream, pClose, new byte[DEFAULT_BUFFER_SIZE]);
	}

	/**
	 * Copies the contents of the given {@link InputStream} to the given {@link OutputStream}.
	 *
	 * @param pIn The input stream, which is being read. It is guaranteed, that {@link InputStream#close()} is called on
	 *            the stream.
	 * @param pOut The output stream, to which data should be written. May be null, in which case the input streams
	 *            contents are simply discarded.
	 * @param pClose True guarantees, that {@link OutputStream#close()} is called on the stream. False indicates, that
	 *            only {@link OutputStream#flush()} should be called finally.
	 * @param pBuffer Temporary buffer, which is to be used for copying data.
	 *
	 * @return Number of bytes, which have been copied.
	 * @throws IOException An I/O error occurred.
	 */
	public static long copy(InputStream pIn, OutputStream pOut, boolean pClose, byte[] pBuffer) throws IOException {
		OutputStream out = pOut;
		InputStream in = pIn;
		try {
			long total = 0;
			for (;;) {
				int res = in.read(pBuffer);
				if (res == -1) {
					break;
				}
				if (res > 0) {
					total += res;
					if (out != null) {
						out.write(pBuffer, 0, res);
					}
				}
			}
			if (out != null) {
				if (pClose) {
					out.close();
				} else {
					out.flush();
				}
				out = null;
			}
			in.close();
			in = null;
			return total;
		} finally {
			if (in != null) {
				try {
					in.close();
				} catch (Throwable t) {
					/* Ignore me */
				}
			}
			if (pClose && out != null) {
				try {
					out.close();
				} catch (Throwable t) {
					/* ignore me */
				}
			}
		}
	}

	/**
	 * This convenience method allows to read a <code>org.apache.commons.fileupload.FileItemStream</code>'s content into a
	 * string. The platform's default character encoding is used for converting bytes into characters.
	 *
	 * @param pStream The input stream to read.
	 * @see #asString(InputStream, String)
	 *
	 * @return The streams contents, as a string.
	 * @throws IOException An I/O error occurred.
	 */
	public static String asString(InputStream pStream) throws IOException {
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		copy(pStream, baos, true);
		return baos.toString();
	}

	/**
	 * This convenience method allows to read a <code>org.apache.commons.fileupload.FileItemStream</code>'s content into a
	 * string, using the given character encoding.
	 *
	 * @param pStream The input stream to read.
	 * @param pEncoding The character encoding, typically "UTF-8".
	 * @see #asString(InputStream)
	 *
	 * @return The streams contents, as a string.
	 * @throws IOException An I/O error occurred.
	 */
	public static String asString(InputStream pStream, String pEncoding) throws IOException {
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		copy(pStream, baos, true);
		return baos.toString(pEncoding);
	}

}
